textproduct: Quad Cities

KEY MESSAGES

- Gradual warming trend begins this weekend and continues next week along with increasing humidity. Heat indices in the mid to upper 90s are likely.

- Active weather returns next week, with periodic chances for showers and storms.

SHORT TERM /THROUGH TONIGHT/

Issued at 149 PM CDT Fri Aug 28 2026

Another beautiful late summer day is unfolding today, with high pressure overhead. Seasonable temperatures in the low 80s and a scattered diurnal Cu field has developed outside as of 1 pm.

High pressure to slide east this evening, with return flow allowing for milder temps tonight in the low 60s and an increase in high clouds.

LONG TERM /SATURDAY THROUGH THURSDAY/

Issued at 149 PM CDT Fri Aug 28 2026

A shortwave and associated weak surface low will track across the Dakotas into MN and northern IA after midnight tonight. Strong moisture transport aided by a 45kt LLJ will allow for scattered showers and thunderstorms to track eastward early Saturday. Forecast soundings and RAP layer RH progs show this activity will encounter quite a bit dry air once it arrives in our northwest. In addition, the terminus and orientation of the LLJ appears to support the bulk of these showers/isolated storms remaining to our north, but perhaps clipping the Hwy 20 corridor near IIB before decaying further as LLJ wanes. Have maintained chance/likely PoPs north of a Cedar Rapids to Dubuque line 12-18z Sat, but this may be too high. Any rain that reaches the ground will be light and less than a tenth of an inch. Some CAMs develop some additional showers during the afternoon/evening across eastern IA, but forecast soundings are rather dry below 700mb and have kept the forecast dry for now.

Something that will be more noticeable through Saturday will be the increasing humidity levels and breezy south winds. Forecast soundings show 30kts at the top of the mixed layer resulting in some gustiness during the afternoon hours. Despite WAA through the day, cloud cover should keep northeast IA/northwest IL cooler in the upper 70s/low 80s, with mid to upper 80s elsewhere.

Sunday-Thursday...active pattern with several shortwaves topping the strong 594 dam ridge leading to building heat and periodic chances for storms. Confidence in the timing of storms remains quite low due to the varying model solutions strength and breakdown timing of the ridge. 00z NAEFS shows this ridge is in the 99th percentile with respect to climatology, which is one of the reasons why CPC has a moderate risk of excessive heat across much of the south central CONUS. LREF probabilities for 850 mb temps greater than 22C are now in the 60-80% range Monday through Thursday and NBM probabilities of 70+ degree dewpoints remain in the 60-80%. This will yield highs in the upper 80s/lower 90s and heat indices in the mid 90s to near 100 degrees. The WPC experimental heat risk product is in Major to Extreme categories Monday through Thursday along and south of I-80 and forecast wet bulb globe temps rise around 86 degrees in the afternoon. Heat headlines may eventually be needed next week for a portion of the area. In addition, some record warm lows may be in jeopardy and have included those in a climate section below.

Regarding storm potential, there is a Day 3 Marginal (level 1 out of 5) risk for severe storms Sunday north of a Ames to Dubuque line. A warm front will be near the IA/MN border Sunday afternoon with building instability (MLCAPEs in the 1200-1700 J/Kg) and more favorable kinematics (0-6 km shear values 40-50 kts) in the warm sector. An EML and marginal mid level lapse rates may limit storm development. If any were to develop, heavy rain and damaging wind would be the primary threats. As is often the case with this ring of fire pattern, assessing severe and heavy rain risk further out past Day 3 is too difficult at this time range. Although some ML guidance is starting to show some signs of low probabilities Tuesday and Wednesday. Something to watch in later forecasts.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1154 AM CDT Fri Aug 28 2026

VFR conditions are expected through the period. Winds to turn southerly after 00z, as high pressure exits into the Ohio river valley. Scattered showers and isolated storms will track across southern MN/northern IA early Saturday and reach eastern IA after sunrise is a dissipating state. Winds to increase and become gusty just beyond TAF cycle.

CLIMATE

Issued at 139 PM CDT Fri Aug 28 2026

Record Warm Low Temperatures:

August 31: KDBQ: 74/2000 KMLI: 75/2000

September 1: KDBQ: 73/1937 KMLI: 75/1913

September 2: KDBQ: 74/2011 KMLI: 77/1913

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.